Electrochemical cell and selfventing enclosure therefor



R. COLTON April 21, 1953 ELECTROCHEMICAL CELL AND SELF-VENTING ENCLOSURE THEREFOR Filed Nov. 19, 1949 ff Z7 l l r INVENTOR :insis- 1705er? 2l/fok Patented Apr. 21, 1953 ELECTROCHEMICAL CELL AND SELF- VENTING ENCLOSURE THEREFOR Robert Colton, New Rochelle, N. Y., assigner to P. R. Mallory & Co., Inc., Indianapolis, Ind., a

corporation of Delaware Application November 19, 1949, Serial No. 128,403

(Cl. 13G-133) 15 Claims. 1

This invention relates to electrochemical cells and, more particularly, to electrical current producing cells, such as primary and secondary cells, and to an improved air-tight enclosure for such cells.

The invention is particularly applicable to dry cells of the type disclosed in U. S. Patent No. 2,422,045, granted to Samuel Ruben. Broadly considered, the cells disclosed in this patent comprise an amalgamated zinc anode, a cathode of a depolarizer material including an electrolytioally reducible oxygen yielding compound, such as electrolytically reducible oxides and perman ganates, and an alkaline electrolyte such as an aqueous solution of an alkali metal hydroxide initially containing a substantial quantity of dissolved zinc. The electrolyte is immobilized against free motion or flow from the anode to the cathode, or vice versa, preferably by means which physically space them apart and comprise absorbent or minutely porous and ionically permeable inert material whereby migration of impurities and deleterious materials from one electrode to the other is inhibited. In alkaline dry cells of the described character, it is of critical importance to provide an airtight enclosure for the cell. An enclosure of such character is desirable rst to positively prevent leakage of the strongly corrosive alkaline electrolyte and also to prevent contact of such 'electrolyte with the atmosphere which would ycause the absorption of carbon dioxide therefrom with subsequent progressive conversion of the lalkali metal hydroxide into an alkali metal carbonate. While under normal conditions no gas is generated in the cell on shelf life or during vactual use, particularly in the presence of small impurities in the cell materials, gas generation may occur, giving rise to substantial increase in internal pressure. If there were no provision made for the release of such pressure, the cell may bulge or be otherwise deformed and in extreme cases may even explode. For this reason, it has been found necessary to incorporate a suitable venting device into the cell enclosure which becomes operative upon the development of excessive internal pressures to release the gases accumulated within the cell enclosure,

The requirements which a venting device had to satisfy were quite exacting. First of all, the device had to assure the desired airntjight sealing of the cell in the absence ofexcessive internal pressure and had to become operative upon the internal pressure exceeding accurately preH determined maximum safe value. Also, device, upon being operated, had to permit the escape of gas while positively preventing the ferential flange l5 around its mouth portion.

simultaneous escape of electrolyte or of reduced mercury from the cell. Finally, it was highly desirable that the venting device automatically restores the original air-tightly sealed character of the cell after the internal pressure had been reduced to a normal or safe value. In the past, considerable diiiiculty was experienced with venting devices of the described character and it was found to be particularly difficult to provide a practical and fully satisfactory venting device having a structure sufficiently simple and inexpensive to be incorporated in primary and secondary cells oi' small size.

It is an object of the present invention to improve venting devices of the described general type.

It is another object of the present invention to provide an electrical current producing cell, such as a primary or secondary cell, comprising a novel and improved venting device.

It is a further object of the invention to provide a novel venting device for electrochemical cells which will positively respond to a predetermined increase in internal pressure to release and to discharge such pressure and which is automatically closed after normal internal pressure has been restored.

Other and further objects and advantages of the invention will become apparent from the following description taken in coniunction with the accompanying drawing, in which:

Figure 1 is a vertical sectional view of a cell embodying the present invention;

Figure 2 is a similar view of a modied embodiment of the present invention; and

Figures 3, 4 and 5 are vertical sectional views, somewhat vfragmentary in character, of further modified embodiments of the invention.

Referring now more particularly to Fig. 1 of the drawing, a preferred embodiment of the invention will be described, as applied to an alkaline dry cell of the general tvpe disclosed in the aforesaid Ruben patent. Reference numeral Hl denotes an anode container or cup formed of a metal having, when amalgamated, a low electrolytic potential difference with respect to zinc, such as copper, or a suitable copper base alloy. Container l0 is of a generally dished. or cup-shaped configuration and is provided with an outwardly extending circumferential flange Il. A body I2 of a suitable anode material. such as amalgamated zinc powder, is compressed with the inner space of the anode container.

. Cathode container I4 is preferably formed of steel, is likewise substantially cup-shaped and is provided with an outwardly extending circum A "of the present invention which is applicable to electrochemical cells having `-fwidely different structural 'and electrochemical arrangements.

'The modified cell shown in Fig.. 2 essentially 'comprises :a first electrode Soup lli) with an out- Ward'ly extending circumferential flange itl, a second electrode cup lill having a similar circumferential fla-nge H5, the said cups being faced into each other and having their cooperating marginal portions or `flanges spaced from each 4other by an interposed elastic insulating and sealing groin-inet H8. It will be noted that the body portion i120 Aor lthe grommet-extends lbetween the iian'ges lli and H5 in the radial 1direction Whereas the sleeve portion |21 of the grommet extends axially of the "cell and surrounds lthe marginal regions of 'electrode cup liti..

An outer container or jacket l'22 completely surrounds elect-rode cup l lll with its bottoni surface in vcontact with the `cor-responding surface of cup lid. The mouth portions of the 'outer container are radially constric-ted or crimped at l2@ around the sleeve portion |21 of the grommet thereby maintaining the entire assembly in a position in which tbe two electrode cups 'define with the interposed grommet an air-tightly sealed internal cell space. A. vent opening |21! is provided in the bottom center of outer con-e tainer l 22 and is in restricted communication with the interspace |27 dened between electrode container lill and outer container 122.

The operation of this modified form of the invention is closely similar to that of the embodiment shown in Fig. l and will be readily understood Without any detailed description. It will be sufficient to state that the two electrode cups are capable of limited axial displacement away from each other in response to the building up of excessive internal pressure. The presence of such pressure and the resulting relative axial displacement of the cups will permit vgas to be discharge underneath body portion lli@ of groinrnet lli? around the edge or flange of electrode container iid into intersnace l2? and finally through vent hole i255 into the atmosphere. Since the bottom portions of 'electrode container H4 'and outer container 122 Aare in pressure contact over 'a substantial area, this will restrict the 'coininunication of interspace 21' with the vent hole to a sufficient extent to prevent escape of any electrolyte together' with the discharged gas. However, as a further safety measure, a body of absorbent material (not shown) be provided in inter-space i2? in the same manner as is shown in Fig. l.

The modification of the invention shown in Fig. 3 is practically identical in structure with that described in connection with Fig. 2 and 'the reference numerals have been used to denote the corresponding parts. However, 'the flange or edge M5 of the second 'electrode container {2i-i is extended inwardly rather than outwardly. Furthermore, the cuter jacket or container 222 is so dirnensioned that it forms a close t with the electr-ode container 211i throughout its circumferential 'and bottom portions. This form of the invention operates in a manner ei;- actly identical to the embodiments of the invention shown in Figs. l and 2. Due to the fact that the interspace between electrode container 2M and the outer container 22 is extremely restricted, it provides some assurance against the escape of any electrolyte together with the released gas so that it is generally unnecessary to provide any absorbent material in such interspace. How- 6 ever, fan extra 'covering fof 'absorbent cardboard may be provided around the cell as an additional protection, in case the electrolyte 'leakage is suf- `ficie'ntlypronounced.

The embodiment 'of the `i'nv'entior'isliovvn in Fig. iicislilzevvise 'closely -similar to the ones 'described in the fforegong 'and particularly to the one shown Fig. 3. However, fin this forni of the invention the vouter container fisfr'epla'ced with a `shell lorf-collar 422'whicl'1 is 'open at both -ends thereof. '@ne end' of this shell is 'radially consti'icted raround 'the :grommet at "42B while its other fend is crimped at i435 around the bottoni Kedgeyof anode container "411i, Itvvill likewise 'be noted that outer shell 'is lnrovided in tightly litltin'g relation around the oi-'rcuniferential portions 'of "electrode `container '4l 4 fthei'ieby defining there- 'Witha l*greatly constri'cted-intersbace. Upon venting,'tl1e gas releasedfroin -the vinner cell space has lto lira-ss through this constricted interspace -into'the atmosphere which will 'provide some protection ragainst Athe escape 'of any electrolyte with 'tl-1e escaping gas. A's 'a further protection, an additional covering fof absorbent cardboard, or 'the like, may be provided around the cell in such a manner `as to surround the regions of the cell 'Where sonic electrolyte leakage may occur. Since the outer shell or jacket 422 'exposes the bottom portion of electrode v'container M4, this bottom surface may directly constitute one of theA terminals of the cell, while the other terminal of the cell is constituted by the first electrode cup 410.

In lthe for-in of ytbeinvention 'shown in Fig. 5, tbe shellor collar holding 'the 'tivo electrode Acups SlQ'fa-'nd 51H5 in the assembled :air-tightly sealed and insu-lated relation 'is reduced to a relatively narrow annular member `or band 522 'whichen- 'circles only 4thefrnargin'al regions -of 'tlre tvvo elec'- t'r'ode cups tlie 4corijespun-'ding `portions of the interposed lgrolnnflet J5-18. 'On'e of band i522 is radially cons'tri'cte'd around the grolnmet at t'z's weile its @therese is *spot welded to the electrode 'container kISI-fi ata number 'of circum- 'fei'enti'a-lly 4spaced spots I'53| 'thereby securing the 'said ba-nd to the `electrode container. From the foregoing description, and dueto its similarity to the 'niodiiications previously described, tire op- 'eration of 'this form' of the invention should be obvious. K

While ythe present invention has 'been described in connection with a fet7 Anr'ef'er'red c'nibodinents thereof, variations and o'dication's may be resorted to by those slril4 'd in the art Without de- Dartiiigf'rom tlie iin'cipl'es o f the present invenL tion. Thus, it tvill be readily appreciated that 4the sealed enclosure and automatic venting device of the invention 'may be used for electrical current producing oeils, such as primary 'or sec'- cndary cells, widely 'diner-ent internal 'strueture and 'chemical composition. Also, the advantage's or the invention are not limited to electrical current producing cells but equal or similar advantages may be obtained in electrochemical cells of other types, such as, for instance, in electrolytic condensers and the like. The bottoni surface of the outer jacket can be ribbed or othervxise reinforced for greater structural strength. Moreover', while all ci tbe structures described in the foregoing include flanged cup members, cups with straight drawn Walls and pinched-o edges could be used with equal or similar results. All of these variations and modcations are con-` sidered to be within the true spirit and scope of the present invention, as disclosed inthe foregoing description and dened by the appended claims.

What is claimed is:

1. An electrochemical cell comprising, in combination, a pair of terminal cups faced into eachA other and having cooperating marginal regions, an insulative grommet having a rst portion interposed between said regions and a second portion, and an outer jacket encircling at least the marginal regions oi said cups, said jacket being nxed at one end with respect to one of said cups and being at the other end radially constricted in a region which is directly overlying and is in direct pressure contact with said second portion of the grommet for applying at saidA l other end axial sealing pressure upon said rst portion of the grommet and radial sealing pressure upon said second portion of the grommet thereby maintaining said cups and the grommet therebetween in air-tightly sealed relation but, capable of limited axial venting displacement away from each other in response to excessive internal pressure, said axial displacement of the cups being effective to decrease the sealing pressure upon said rst portion of the grommet and to increase the sealing pressure upon said second portion of the grommet whereby said pressure is released around the edge ci one cup into the inter-space between said cup and jacket while direct .release of said pressure into the exterior is prevented.

2. An electrochemical cell comprising, in cornbination, positive and negative cell terminals having cooperating marginal edges, at least one of said terminals being cup-shaped, an insulative grommet having a body portion extending between said edges radially of the cell and a sleeve portion extending generally axially of the cell, and an annular member encircling the marginals regions of said termin-als and radially constricted in a region which is directly overlying and is in direct pressure contact with said sleeve portion of the grommet for holding the body portion of the grommet under axial compression and the sleeve portion of the grommet under radial compression.

3. An electrochemical cell comprising, in combination, a pair of terminal cups, the marginal regions of said cups including portions extending axially of the cell and cooperating flanges, an

insulative grommet having a body portion interposed between said anges and a sleeve p0rtion hugging the adjoining axially extending portion of one cup, and an annular jacket member encircling the said marginal regions of the cups,

said jacket member being secured against axial displacement with respect to one of said cups and being radially constricted in a region which is dir ctly overlying and is in direct pressure cont-act with the sleeve portion of said grommet thereby holding the body portion of the grommet under axial compression and the sleeve portion of the grommet under radial compression thus maintaining said cups in sealed but electrically insulated relation.

4. An electrochemical cell comprising, in combination, a pair of dished terminal members, the maginal regions of said members including outwardly flared edges, an insulative grommet having a body portion interposed between said edges and a sleeve portion hugging the adjacent portion of one terminal member, and a jacket encircling said terminal members at least in the general region of said grommet, said jacket being fixed against axial displacement fil) with respect to one of said terminal members and being radially constricted over the sleeve portion of said grommet thereby to hold said terminal members in sealed electrically insulated relation but capable oi' limited axial displacement with respect to each other in response to internal pressure.

5. An electrochemical cell comprising, in combination, a pair of metal cups having flared cooperating nanges, an elastic annular grommet having a body portion interposed between said nanges radially of the cell and a sleeve portion, and a metal jacket encircling said cups at least in the region of said grommet, said jacket being substantially xed against axial displacement with respect to one of said cups and being radially constricted in a region which is directly overlying and is in direct pressure contact with the sleeve portion of said grommet at a level spaced from the plane deiining the inner space of one cup from that of the other thereby holding the body portion of said grommet under axial compression and the sleeve portion of the grommet under radial compression thus maintaining said cups in sealed insulative relation but capable of limited axial venting displacement with respect to each other in response to excessive internal pressure.

6. An electrical current producing cell comprising, in combination, la pair of metal cups having cooperating flanges, an annular sealing grommet having a body portion interposed between said anges radially of the cell and a sleeve portion extending axially around one of said cups, and an outer jacket completely encasing the other one of said cups and having its mouth portions radially constricted around the sleeve portion of said grommet, said jacket maintaining said cups and the grommet therebetween in sealed insulative relation but capable of limited axial displacement with respect to each other in response to excessive internal pressure to release gas into the space defined between said jacket and the cup therein.

'7. An electrical current producing cell comprising, in combination, a iirst metal cup and a second metal cup having cooperating pressure faces, cell electrodes of opposite polarity in respective contact with the inner surfaces of said cups, an annular sealing grommet having a body portion interposed between said pressure faces of the cups and a sleeve portion encircling the adjoining region of the first cup, and an outer metal container completely encasing said second cup and in electrical contact therewith, said container having its mouth portions radially constricted around the sleeve portion of said grommet thereby maintaining said cups and the grommet compressed therebetween in insulative sealing relation but capable of limited axial displacement away from each other in response to excessive internal pressure to release gas around the edge of said second cup into the interspace between said second cup and said outer container,

, said first cup and said outer container respectively constituting the two terminals of the cell.

8. An electrical current producing cell comprising, in combination, a rst and a second metal cup having cooperating flared mouth portions faced into each other, cell electrodes of opposite polarity in respective contact with the inner Surfaces of said cups, an annular sealing grommet having a portion radially extending between the mouth portions of said cups and a portion axially extending therefrom around said rst cup, an

9. outer metal container completely enclosing said second cup with portions thereof in electrical contact with and portions thereof spaced from said cup, said container having its mouth portions radially constricted around the axially extending portion of said grommet thereby holding said cups and the grommet compressed therebetween in insulative sealing relation but capable of limited axial displacement away from each other in response to excessive internal pressure to release gas around the edge of said second cup into the interspace between said second cup and said outer container, and a venting opening in said container maintaining said interspace in restricted communication with the atmosphere, said first cup and said outer container respectively constituting the two terminals of the cell.

9. An electrical current producing cell according to claim 7 wherein a body of electrolyte absorbent material is provided in the interspace between the outer container and one of the metal cups.

l0. An electrical current producing cell comprising, in combination, a iirst and a second metal cup respectively having an outwardly and an inwardly bent flange, an annular grommet having a portion radially extending between said iianges and a sleeve portion axially extending therefrom around the rst cup, an outer container completely j acketing said second cup in closely tting contacting relation and having its mouth portions radially constricted around the sleeve portion of the grommet, and a vent opening in said container remote from its mouth portions, said outer container maintaining said cups and the grommet therebetween in insulated sealing relation but capable of limited axial displacement to release excessive internal pressure through the interspace between said container and said second cup and through said vent opening, the said interspace being sufciently restricted to prevent the escape of electrolyte.

11. An electrical current producing cell comprising, in combination, a first and a second metai cup having cooperating flange portions facing each other, cell electrodes of opposite polarity in respective contact with the inner surfaces of said cups, an annular sealing grommet having a portion radially extending between the flange portions of said cups and a portion extending axially therefrom around said first cup, a third metal cup completely jacketing said second cup in closely itting contacting relation and having its mouth portions radially constricted around the axially extending portion of y said grommet thereby holding said rst and second cups and the grommet compressed therebetween in insulative sealing relation but capable of limited axial displacement away from each other in response to excessive internal pressure to release gas around the edge of said second cup into the interspace between said second and third cups, and a vent opening in said third cup permitting the escape of such released gas into the atmosphere while preventing the escape of electrolyte as a result of the greatly constricted character of said interspace, said rst and third cups respectively constituting the two terminals of the cell.

12. An electrical current producing cell comprising, in combination, a first and a second metal cup respectively having an outwardly and an inwardly bent iiange, an annular grommet having a portion radially extending between said :flanges and a sleeve portion axially extending therefrom around the first cup. and an outer shell open at both ends completely surrounding the circumferential portions of said second cup in closely tting contacting relation, one end of said shell being radially constricted around the sleeve portion of said grommet and the other end of said shell being bent inwardly to engage the marginal bottom portions of said second cup, said shell maintaining said cups and the grommet therebetween in insulative sealing relation but capable of limited axial venting displacement from each other in response to excessive internal pressure.

13. An electrical current producing cell comprising, in combination, a first and a second metal cup respectively having an outwardly and an inwardly bent flange, an annular grommet having a portion radially extending between said iianges and a sleeve portion axially extending therefrom around the iirst cup, and an annular jacket around the marginal portions oi said cups in the region of said grommet, one end of said jacket being radially constricted around the sleeve portion of said grommet and the other end of said jacket being secured to said second cup, said jacket maintaining said cups and the grommet therebetween in insulative sealing relation but capable of limited axial displacement to permit the escape of gas from the cell enclosure around the edge of said second cup and through the interspace between said second cup and said jacket.

14. The electrical current producing cell according to claim l2 wherein one end of the annular jacket is spot-welded to the corresponding cup at circumferentially spaced points.

15. An electrochemical cell comprising, in combination, nrst and second terminal cups faced into each other and having cooperating marginal regions, an elastic insulative grommet having a body portion interposed between said regions and a sleeve portion extending around the circumferential surface of the first cup, and an outer jacket encircling at least the marginal regions of both cups, said jacket being iixed at one end with respect to the second cup and being at the other end radially constricted in a region which is directly overlying and is in direct pressure contact with the sleeve portion of said grommet whereby said elastic sleeve portion is radially compressed between said constricted portion of the jacket and the circumferential siuface of said rst cup dening a radially stressed seaiing zone for the cell, said constricted portion of the jacket being further effective in pulling said cups towards each other with the body portion of said grommet therebetween thereby denning an axially stressed sealing zone for the cell.

ROBERT COLTON.

References Cited in the nie of this patent UNITED STATES PATENTS Number Name Date 2,060,799 Drummond Nov. 17, 1936 2,174,437 Collins Sept. 26, 1939 2,289,249 Deibel July 7, 1942 2,307,763 Deibel Jan. 12, 1943 2,457,810 Ellis Jan. 19i9 2,487,985 Ruben Nov. 15, 1949 2,499,239 Williams, Jr Feb. 28, 1950 2,509,249 Rhodes May 30, 1950 2,571,616 Ruben Oct. 16, 1951 FOREIGN PATENTS Number Country Date 561,820 Great Britain Jan. 6. 1944 

1. AN ELECTROCHEMICAL CELL COMPRISING, IN COMBINATION, A PAIR OF TERMINAL CUPS FACED INTO EACH OTHER AND HAVING COOPERATING MARGINAL REGIONS, AN INSULATIVE GROMMET HAVING A FIRST PORTION INTERPOSED BETWEEN SAID REGIONS AND A SECOND PORTION, AND AN OUTER JACKET ENCIRCLING AT LEAST THE MARTINAL REGIONS OF SAID CUPS, SAID JACKET BEING FIXED AT ONE END WITH RESPECT TO ONE OF SAID CUPS AND BEING AT THE OTHER END RADIALLY CONSTRICTED IN A REGION WHICH IS DIRECTLY OVERLYING AND IS IN DIRECT PRESSURE CONTACT WITH SAID SECOND PORTION OF THE GROMMET FOR APPLYING AT SAID OTHER END AXIAL SEALING PRESSURE UPON SAID FIRST PORTION OF THE GROMMET AND RADIAL SEALING PRESSURE UPON SAID SECOND PORTION OF THE GROMMET THEREBY MAINTAINING SAID CUPS AND THE GROMMET THEREBETWEEN IN AIR-TIGHTLY SEALED RELATION BUT CAPABLE OF LIMITED AXIAL VENTING DISPLACEMENT AWAY FROM EACH OTHER IN RESPONSE TO EXCESSIVE INTERNAL PRESSURE, SAID AXIAL DISPLACEMENT OF THE CUPS BEING EFFECTIVE TO DECREASE THE SEALING PRESSURE UPON SAID FIRST PORTION OF THE GROMMET AND TO INCREASE THE SEALING PRESSURE UPON SAID SECOND PORTION OF THE GROMMET WHEREBY SAID PRESSURE IS RELEASED AROUND THE EDGE OF ONE CUP INTO THE INTERSPACE BETWEEN SAID CUP AND JACKET WHILE DIRECT RELEASE OF SAID PRESSURE INTO THE EXTERIOR IS PREVENTED. 